If you have a SMN or BLM in the group, easiest way is for a couple pulls have provoke ready. If they are always doing nothing but AOE, which I find almost all SMN do, then switch to a different rotation then normal. Use flash after every ROH combo for starters. You also want to constantly tab check on every mob and see which ones have the highest chance of getting pulled by the SMN/BLM. Save your ROH for that mob, and continue regular rotation with adding flash more then normal during a non-SMN/BLM run.

You can see how much threat everyone has on a specific mob under the party menu. It helps tremendously to see which person is about to pull aggro so you can react to it.